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The Java operations layer for the MongoDB Java Driver.
Third parties can wrap this layer to provide custom higher-level APIs
/*
* Copyright 2008-present MongoDB, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.mongodb.internal.connection;
import com.mongodb.MongoInternalException;
import java.util.HashMap;
import java.util.Map;
import static com.mongodb.assertions.Assertions.isTrueArgument;
/**
* Efficiently maps each integer in a set to another integer in a set, useful for merging bulk write errors when a bulk write must be
* split into multiple batches. Has the ability to switch from a range-based to a hash-based map depending on the mappings that have
* been added.
*
* This class is not part of the public API and may be removed or changed at any time
*/
public abstract class IndexMap {
/**
* Create an empty index map.
*
* @return a new index map
*/
public static IndexMap create() {
return new RangeBased();
}
/**
* Create an index map that maps the integers 0..count to startIndex..startIndex + count.
*
* @param startIndex the start index
* @param count the count
* @return an index map
*/
public static IndexMap create(final int startIndex, final int count) {
return new RangeBased(startIndex, count);
}
/**
* Add a new index to the map
*
* @param index the index
* @param originalIndex the original index
* @return an index map with this index added to it
*/
public abstract IndexMap add(int index, int originalIndex);
/**
* Return the index that the specified index is mapped to.
*
* @param index the index
* @return the index it's mapped to
*/
public abstract int map(int index);
private static class HashBased extends IndexMap {
private final Map indexMap = new HashMap<>();
HashBased(final int startIndex, final int count) {
for (int i = startIndex; i < startIndex + count; i++) {
indexMap.put(i - startIndex, i);
}
}
@Override
public IndexMap add(final int index, final int originalIndex) {
indexMap.put(index, originalIndex);
return this;
}
@Override
public int map(final int index) {
Integer originalIndex = indexMap.get(index);
if (originalIndex == null) {
throw new MongoInternalException("no mapping found for index " + index);
}
return originalIndex;
}
}
private static class RangeBased extends IndexMap {
private int startIndex;
private int count;
RangeBased() {
}
RangeBased(final int startIndex, final int count) {
isTrueArgument("startIndex", startIndex >= 0);
isTrueArgument("count", count > 0);
this.startIndex = startIndex;
this.count = count;
}
@Override
public IndexMap add(final int index, final int originalIndex) {
if (count == 0) {
startIndex = originalIndex;
count = 1;
return this;
} else if (originalIndex == startIndex + count) {
count += 1;
return this;
} else {
IndexMap hashBasedMap = new HashBased(startIndex, count);
hashBasedMap.add(index, originalIndex);
return hashBasedMap;
}
}
@Override
public int map(final int index) {
if (index < 0) {
throw new MongoInternalException("no mapping found for index " + index);
} else if (index >= count) {
throw new MongoInternalException("index should not be greater than or equal to count");
}
return startIndex + index;
}
}
}
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